The present invention relates to coating compositions and in particular, relates to protective coating compositions for polymeric materials.
In recent years, synthetic polymeric materials have been utilized in a wide variety of applications. Transparent polymeric materials have been utilized as windows in aircraft and public buildings. Further, transparent polycarbonates and acrylics have been utilized in glazing for automobiles, buses and aircraft. Although these transparent polymers may be readily fabricated into the desired shape, unfortunately they have relatively low abrasion resistance. The prior method of enabling the use of these transparent polymers involves coating the surface of the polymers with a transparent, abrasion-resistant coating. Prior coating such as silica-containing solutions and polysilicic acid fluorinated copolymer have been utilized. Unfortunately, these coatings are difficult to apply, have a low humidity resistance or are expensive.
Another prior coating composition is disclosed in the Clark U.S. Pat. No. 3,986,997. The Clark composition comprised a colloidal dispersion of silica in a water-alcohol solution of the partial condensate of silanol. Although the Clark composition is suitable in some applications, in other applications, additional hardness, elongation and static dissipation was desired to enable the formation of a more suitable coating. Thus, a coating having an improved hardness, elongation and static dissipating capability is still desired.